Camera classes: modified and implemented the 'setFramerate' function.

The function now returns the framerate set on the camera (which might be
different than the one required at the function call, depending on
hardware limitations).

The 'getFramerate' function returns the framerate of the camera.
main: Added getopt_long support.

The program now accepts options starting with a double dash (--). This
will be used to specify complex input parameters.
main: Integrated all command-line option variables in a struct.

The 'ProgramOpts' structure holds all flags and values set by
command-line argument. This improves the readability of the code.
UEye: Implemented the ring buffer mapping.
Camera class: fixed the parameters of the 'acquire' method.
I2C: Created the 'I2CBus' class.

This class manages the reception and handling of I2C messages.
I2C: Added the 'RXThread' class.

This class parses I2C messages and translates them in orders for the camera acquisition subsystem.
I2C: Added the two I2C files to the list of compiled files.

Fixed an error in the 'RXThread' class definition.
Merge branch 'master' into multiple_acquisitions

Conflicts:
	include/camera.hpp
	src/main.cpp
main: Fixed a problem with program parameters caused by the merge.
Camera classes: Renamed the 'acquire method'.

The method is now called 'start' and a new 'stop' method was declared.
These methods are called from another thread to start and stop the camera
acquisition.
uEye camera: declared the 'uEyeEventListener' thread static method.
uEye Camera: added references to the pthread library.

The event listener will be managed through a thread using the pthread lib.
Makefile: The program is now linked with the pthread library.
Unit tests: Fixed a library dependency order in the Makefile.
uEye Camera: started the implementation of the event listening thread.
Merge branch 'multiple_acquisitions' of https://github.com/RexusCWIS/camera_module into multiple_acquisitions
uEye camera: Added some basic event management.
Defined the 'UEye_EventThread' class.

This class defines event handler threads for the uEye camera class.
uEye Event thread: Error fixing.

Fixed some compilation errors.